Whipstock and starter mill

Abstract

A mill kick out apparatus comprises a whipstock and a starter mill. The whipstock has a lower end pivotally connected to a supporting assembly, an upper end, an outer side for disposition adjacent one side of a well wall, and an inner side diametrically opposite the outer side. The outer side has a vertically elongate upper portion angularly disposed with respect to a lower portion thereof, whereby the upper portion may abut the one side of the well wall when the lower portion is inclined downwardly and inwardly with respect thereto. The inner side is configured to be disposed at a first downward and inward angle with respect to the one side of the well wall when the one side so abuts the upper portion of the outer side of the whipstock. A lug projects generally radially inwardly from the inner side of the whipstock adjacent the upper end and has a generally radially inwardly facing surface disposed at a second downward and inward angle with respect to the one side of the well wall. The length of a primary portion of the lug surface is no greater than the length of the upper portion of the outer side of the whipstock. The starter mill is longitudinally movable with respect to the whipstock and comprises a rotary milling tool and a nose piece disposed below the milling tool. The nose piece has an upper portion of greater diameter than the distance between a lower part of the lug and another side of the well wall opposite the one side. The milling tool and the nose piece are relatively rotatable.

What is claimed is: 
     
       1. A mill kick out apparatus comprising: a whipstock having   a lower end pivotally connected to a supporting assembly;   an upper end;   an outer side for disposition adjacent one side of a well wall and having a vertically elongate upper portion angularly disposed with respect to a lower portion thereof, whereby the upper portion of the outer side may abut the one side of the well wall when the lower portion is inclined with respect to the upper portion and is radially spaced from said one side of the well wall;   an inner side diametrically opposite the outer side and configured to be disposed at a first angle with respect to the one side of the well wall when the upper portion of the outer side of the whipstock abuts the one side of the well wall; and   a lug projecting generally radially inwardly from the inner side of the upper end of the whipstock and having a facing surface disposed at a second angle inclined with respect to both the first angle and with respect to the one side of the well wall, an axial length of the facing surface being no greater than an axial length of the upper portion of the outer side of the whipstock.   
     
     
       2. The apparatus of claim 1, wherein the second angle is greater than the first angle. 
     
     
       3. The apparatus of claim 1, wherein the upper end of the whipstock above the lug includes an upper surface angled to form a continuation of the facing surface. 
     
     
       4. The apparatus of claim 3, wherein the combined axial length of the upper surface on the upper end of the whipstock and the facing surface is less than the axial length of the upper portion of the outer side of the whipstock. 
     
     
       5. The apparatus of claim 1, wherein the lug has a vertically elongated channel recessed radially thereinto. 
     
     
       6. The apparatus of claim 1, wherein the whipstock is of the through-tubing type. 
     
     
       7. The apparatus of claim 1, further comprising: starter mill apparatus having a central axis and longitudinally movable with respect to the whipstock and engageable with the facing surface, the starter mill apparatus including a rotary milling tool and a nose piece disposed below the milling tool.   
     
     
       8. The apparatus of claim 7, wherein the nose piece is tapered radially inwardly toward the central axis from the juncture with the milling tool. 
     
     
       9. The apparatus of claim 8, wherein the nose piece has an upper portion of greater diameter than the distance between a lower portion of the facing surface and another side of the well wall opposite the one side. 
     
     
       10. The apparatus of claim 9 comprising a rotary motor operatively connected to the milling tool and a length of coil tubing extending upwardly from the motor. 
     
     
       11. The apparatus of claim 7, wherein the nose piece has an upper portion of greater diameter than the distance between a lower portion of the facing surface and another side of the well wall opposite the one side. 
     
     
       12. The apparatus of claim 11, wherein the milling tool and the nose piece are relatively rotatable. 
     
     
       13. The apparatus of claim 7, wherein the milling tool and the nose piece are relatively rotatable. 
     
     
       14. A mill kick out apparatus comprising: a whipstock having   a lower end pivotally connected to a supporting assembly;   an upper end;   an outer side for disposition adjacent one side of the well wall;   an inner side diametrically opposite the outer side and having a face surface adjacent the upper end disposed at a downward and inward angle with respect to the one side of the well wall; and   starter mill apparatus longitudinally movable with respect to the whipstock and comprising a rotary milling tool and a nose piece disposed below and rotatable independently of the milling tool, the nose piece having an upper portion of greater diameter than the distance between a lower end of the face surface and another side of the well wall opposite the one side.   
     
     
       15. The apparatus of claim 14, wherein the nose piece is tapered from a juncture with the milling tool. 
     
     
       16. The apparatus of claim 15 further comprising: a rotary motor operatively connected to the milling tool and a length of coil tubing extending upwardly from the motor.   
     
     
       17. The apparatus of claim 16, wherein the milling tool and the nose piece are relatively rotatable. 
     
     
       18. A starter mill apparatus for milling laterally into one side of a well casing, comprising: a rotary milling tool and a nose piece disposed below the milling tool, the milling tool and the nose piece being relatively rotatable.   
     
     
       19. The apparatus of claim 18, wherein the nose piece is tapered from the juncture with the milling tool.